Meanwhile, we've heard that Spotify is likewise finding it difficult to raise yet another round of funding at a multibillion dollar valuation.

New York ad tech firm AppNexus, talked about as though it is a very successful company worth billions to a buyer, also spent the past few months looking at term sheets with valuations lower than its management had expected to see.

What's going on?

Fallout from the Facebook IPO, is what. It didn't go as planned for lots of late stage investors who bought into the company at a very high valuation during its last few years as a private enterprise.

General Atlantic, for one, bought in at $65 billion valuation in March 2011. That's right around Facebook's market cap now.

One person close to these kinds of late stage startup investments says that late stage investors are actively bringing up the Facebook IPO in negotiations with other late stage startups in an effort to drive down valuations.

"Potential investors are trying to use it to depress value - why not?"

Another source, this one a prominent Silicon Valley VC, says the Facebook IPO was "a reality check" on the "trivialization of the billion dollar valuation."

"The world is waking up that 'the sky is the limit" doesn't work."

Our first source - one who helps startups fund raise - says that some late stage startups are holding off on fundraising till the Facebook deal moves from the forefront a bit.

He believes it will in the medium term.

"Water will find its level. No company is powerful enough to affect the entire market."